That beer should be very dark, like a stout color, if that's what you're going for. The crystal 60L will make it dark, not just the black patent, and the amber DME will also make it dark. If that's what you're looking for, a black lager, you can still get it by cutting the black patent to one or two ounces.
Broken Leg Brewery
Giving beer a leg to stand on since 2006